The general class of polymers of carbon monoxide and one or more ethylenically unsaturated hydrocarbons has been known for some years. Brubaker, U.S. Pat. No. 2,495,286, produced such polymers of relatively low carbon monoxide content in the presence of free radical initiators such as benzoyl peroxide. British Patent 1,081,304 produced such polymers of higher carbon monoxide content in the presence of alkylphosphine complexes of palladium as catalyst. Nozaki extended the process to produce linear alternating polymers in the presence of arylphosphine complexes of palladium. See, for example, U.S. Pat. No. 3,694,412.
More recently, the class of linear alternating polymers of carbon monoxide and at least one ethylenically unsaturated hydrocarbon has become of greater interest in part because of the availability of the polymers. These polymer, often referred to a polyketone or polyketone polymers have been shown to be of the repeating formula --CO--(A)-- where A is the moiety of an ethylenically unsaturated hydrocarbon polymerized through the ethylenic unsaturation. For example, when the ethylenically unsaturated hydrocarbon is ethylene the polymer will be represented by the repeating formula --CO--(CH.sub.2 --CH.sub.2)--. The general process for the more recent production of such polymers is illustrated by a number of published European Patent Applications including 121,965 and 181,014. These process typically involves a catalyst composition formed from a compound of the group VIII metals palladium, cobalt or nickel, the anion of a strong non-hydrohalogenic acid having a pKa below 6 and a bidentate ligand of phosphorus, arsenic or antimony.
The resulting polymers are relatively high molecular weight thermoplastics having utility in the production of shaped articles such as containers for the food and drink industry. For some particular applications it has been found to be desirable to have properties of a polymeric composition modified to reduce water vapor through the polymer. The present invention provides a process for treating the polymer so as to retain the more desirable properties of the polyketone polymer and yet improve other properties.